Tuesday, 4 June 2013

1. In the circuit below, the diode is ideal. The voltage V is
given by

(A) Min (Vi,1) (B)
max (Vi,1)

(C)
min(-Vi,1) (D) max
(-Vi,1)

2. Consider the following two statements about the internal
conditions in an n-channel MOSFET operating

in the active region.

S1 :
The inversion charge decreases from source to drain

S2 :
The channel potential increases from source to drain

Which of the following is correct ?

(A)Both S1 and S2 is true

(B)Both S1 and S2 is false

(C)Both S1 and S2 is true, but S2 is not a reason
for S1

(D)Both S1 and S2 is true, and S2 is a reason for
S1

Common Data Questions for 3 and 4 :

Consider a silicon P-N junction at room temperature having
the following parameters :

Doping on the n-side = 1 x 1017 cm-3

Depletion width on the n-side = 0.1 um

Depletion width on the p-side = 1.0 um

Intrinsic carrier concentration = 1.4 x 1010 cm-3

Thermal voltage = 26 mV

Permittivity of free space = 8.85 x 10-14 F.cm-1

Dielectric constant of silicon = 12

3. The built in potential of the junction is

(A)0.70 V (B)
0.76 V (C) 0.82 V

(D)
cannot be estimated from the given data

4. The peak electric field in the device is

(A)0.15 MV.cm-1, directed from p-region to
n-region

(B)0.15 MV.cm-1, directed from n-region to
p-region

(C)1.80 MV.cm-1, directed from p-region to
n-region

(D)1.80 MV.cm-1, directed from n-region to
p-region

Linked Questions : 5 and 6

Consider the CMOS circuit shown, where the gate voltage VG
of the n-MOSFET is increased from zero, while the gate voltage of the p-MOSFET
is kept constant at 3 volts. Assume that , for both transistors, the magnitude
of the threshold voltage is 1 volt and the product of the trans conductance
parameter and the (W/L) ratio, i.e. the quantity µCox.(W/L) is 1 mA.
V-2.

5. For small increase in VG beyond 1 Volt, which of
the following fives the correct description of the region of operation of each
MOSFET ?